Expandable countertop oven

ABSTRACT

A rapid cooking method is provided in which food pieces are contacted with an air stream at a velocity of at least 1,000 linear feet per minute. 
     Rapid cooking equipment is disclosed which creates high velocity air current.

This is a continuation of U.S. patent application Ser. No. 325,157 filedMar. 17, 1989, pending, which is a continuation-in-part of U.S. Pat.application Ser. No. 014,997, filed Feb. 17, 1987, now issued as U.S.Pat. No. 4,817,509.

FIELD OF THE INVENTION

The present invention relates to methods for cooking of food productsand more particularly to method for cooking using a high velocity aircurrent to rapidly cook the food product.

BACKGROUND OF THE INVENTION

A wide variety of cooking methods and cooking devices have been providedin the past. Deep fat frying and broiling are illustrative of methods ofcooking that have been around for years. The conventional oven is alsoillustrative of cooking devices that have been in use for many years. Infact, simple ovens in various forms have been in use for centuries inhomes, commercial bakeries, institutional kitchens and restaurants.

Conventional ovens have been provided in a variety of models and sizes,for example, a permanent, built-in style, mounted in cabinetry, togetherwith or independent of a stove top unit. Conventional ovens have alsobeen provided of a portable design. While the conventional oven remainsa basic essential cooking unit in the home as well as restaurants or thelike, conventional ovens do have their shortcomings. Conventional ovens,for example, tend to cook slowly and thus consume a good of the user'stime.

Attempts have been made to overcome this problem; for example, microwaveovens have become popular. While microwave ovens cook rapidly, they toohave their shortcomings. For example, it is difficult to brown food in amicrowave oven.

Other attempts at solving the slowness of conventional ovens have beento include a circulating fan to move the air in the oven. While suchcirculating fans have provided more rapid cooking, the time required isstill very substantial. Such existing ovens perform their tasks in asimilar way. The majority of such cooking devices consist of arectangular oven, usually equipped with a plurality of racks, much likethat found in conventional in-home ovens. Often at the rear of the ovenis a squirrel-cage type blower which draws the air through a hole in theinterior rear wall and blows the air out to the sides where it isdirected to perforations in the two interior side walls. Thispressurized air is then forced through the perforations toward the rearcenter o the oven enclosure, where it is drawn into the blower intakehole and recirculated, thereby completing a closed loop. An ovenproduced by Rair follows the above pattern with the exception ofcirculating the air through a cylindrical chamber with its axispositioned horizontally.

Air velocities within the cooking chamber of such ovens are low incomparison to the present method and vary widely within each oven. Thevelocities are generally the highest immediately in front of the blowerintake. A typical average air speed found in a commercial restaurantconvection oven is approximately 350 feet per minute.

A conventional square or rectangular chamber, especially with sharpcorners, offers great resistance to the smooth flow of air due to theabrupt change in direction of the air stream at each corner encountered.This makes it difficult for conventional ovens to achieve the airvelocities of the present invention. Turbulence is created inconventional chambers as well as stagnant areas of relatively cool airin the corners and thus the air velocities are difficult to obtainwithout displacement of the food pieces. Earlier forced air designs makeuse of large blowers and powerful motors to pressurize the air and forceit as evenly as possible through the cooking chamber, usually throughperforations or louvers in the interior walls of the cooking chamber.Such prior devices have not been effective to produce the results foundin the present invention since they do not achieve the necessaryvelocities. Also such high power devices are not practical whendesigning a lightweight portable appliance, due to the excessive noise,added cost and space requirements of such a design.

Prior ovens with fans have not been able to get their fans to achievehigh rates of speed for the two following reasons. Ovens with fans oftendisrupt or restrict their air flow in one or both of two ways:

The prior ovens disrupt or restrict the fans air output by forcing theair through a grease filter. The function of that filter is typically toprotect the fan from grease. The present fan is self-cleaning and doesnot have the problem of having to restrict air velocities by facing theair through a grease filter.

Prior ovens also disrupt or restrict the air flow by placing the heatingelements so that the air coming off the fan blades passes over andaround the heating element. This is done to heat the air, but it alsoseverely disrupts the air flow making it more difficult to achievehigher, free-flow air velocities. The present invention disposes theheating element behind the fan in a position where it does not disruptor restrict the air flow, thus achieving higher rates of air flow withbetter results.

Prior ovens with fans do not extend the fans down into the cookingchamber. The fans are generally recessed into the wall of the cookingchamber or into the roof of that cooking chamber. The fans are thereforecovered by or partially blocked by either the wall, a filter, of someother enclosure or housing.

The fan blade in the present invention projects into the cooking chamberwhere it drives the air free and unrestricted by any enclosure. It isthe position of the present fan within or relative to the chamber thatcontributes to its ability to achieve the high air velocities and theattendant results.

Various means of heating the air are used, usually employing natural gasheat exchangers located in the sides of the oven or electrical tubularheating elements located in the lower portion of the oven.

A rapid cooking device has been the deep fat fryer. Such fryers aretypically used to prepare French fries, breaded shrimp, fried chickenand the like. Deep fat fryers will typically cook food pieces in fromone to five minutes. Deep fat fryers brown the product and developdesirable flavor characteristics. Deep fat fryers, however, also haveinherent disadvantages. One such inherent disadvantage is the fact thatthe cooked food product has very high levels of fats, thus increasingthe caloric content as well as the potential adverse effects ofcholesterol on the consumer's circulatory system.

SUMMARY OF THE INVENTION

The present cooking method provides a very rapid and a very high rate ofheat exchange cooking using high velocity air streams. The presentinvention achieves results very similar to baking, frying, broiling,rotisserie cooking, toasting, boiling, microwave, range cooking,however, with improved results. One may simultaneously bake a cinnamonroll, fry bacon and boil an egg.

Any of a wide variety of foods may be cooked using the preset method,for example, meats, eggs, various forms of potatoes (e.g., baked,american fries), breads (e.g., dough pieces for bread loaves, sweetrolls and the like). The air stream may be provided in any type ofapparatus capable of producing the velocities while avoidingdisplacement of the food pieces. The necessary conditions of temperatureand air velocities may be provided in a cylindrical cooking chamber ofthe type shown in U.S. Pat. No. 4,817,509. Such cooking device desirablyhas a patterned air current, e.g. cyclone shape, although a somewhatturbulent air flow is acceptable so long as the air velocities can bemaintained at the necessary level. The air frier shown in U.S. Pat. No.4,817,509 has a cylindrical cooking chamber with gentle radii in theupper and lower corners to facilitate smooth air flow around thesecorners. The round shape of the chamber unlike conventional air streamovens, works in cooperation with an elevated air stream velocity, ratherthan against the air flow.

The present invention provides a solution to the various problemsconfronted by previous methods of cooking including methods usingconvection ovens as well as the deep fat fryers. The present inventionprovides very rapid cooking, develops browning and flavoring of thecooked product, and will provide products similar to those typicallydeep fat fried but with controlled oil content.

The present invention in its preferred form may be carried out using anair frier with a lower or bottom unit which has a circularcircumferential wall and a lower integral wall. The lower unit has arack on which the food pieces may be placed for cooking purposes. A holddown rack may overlie the food pieces during cooking thereby permittinghigher air velocities. The unit may include a top portion which likewisehas a circumferential wall and an integral top wall. An opening may bedefined in the central portion of the top wall into which a poweredheater may be removably mounted. A small vent may draw moisture ladenair from said top portion to increase the cooking rate.

The powered heating unit heats an air stream and moves the air streamwithin the chamber defined by the lower unit and the upper unit at veryhigh velocities, for example, in excess of 1,000 linear feet per minute,e.g., typically 1200 to 2500 linear feet per minute. The apparatus mayinclude mechanism to adjust the air velocity and temperature to achieveoptimum cooking conditions. The air stream flowing past the heater coilmaintains the heater coil at a temperature such that the coil remainsblack. Desirably, the air flow in the cooking chamber is in a cycloneconfiguration. The direction of air flow may be periodically reversed tofacilitate uniform cooking.

The two portions of the unit may form a clam-shell structure and may behingedly connected so that the top may be pivoted upwardly to provideaccess to the rack. The hinged connection may provide a positiveelectrical disconnect to prevent operation to the blower or heatingelement when the top is pivoted upwardly.

The cooking device enclosure may be moded in a high temperature plasticas two pieces, a top and a bottom. Construction of the device of plasticpermits temperatures in the chamber 400° F. and higher while avoidingdanger of burning the user should the user touch the plastic, e.g. thetemperature drop across the plastic wall is substational where as thiswould not be the case with glass or metal. A single round wire orplastic rack may be supported in the bottom half. The height of the rackmay be adjusted up or down to meet the needs of different sized foodpieces. In order to accommodate taller items such as loaves of bread orturkeys, the user may add one or more extension rings between the upperand lower halves of the cooking enclosure. Extension segments may alsobe added to the high support assembly to match the extended height ofthe cooking enclosure.

By removing the rack and detaching the blower and hinge assembly, thecooking enclosure may be used as an oven-proof casserole dish or anattractive serving dish. With molded-in feet, the enclosure may beplaced on the dining table without the need of a trivet.

The use of a plastic or polymeric cooking enclosure provides a lowthermal mass for rapid heat up and cool down, low thermal conductivityto slow heat loss and reduced risk of burns to the user, and lightweightfor low cost shipping, easy portability and convenient use.

The device may have a transparent plastic top for clear observation offood while cooking, a low risk of breakage or cuts from broken pieces,and resistance to dents, chips, scratches or sharp edges found onpainted metal parts.

IN THE DRAWINGS

FIG. 1 is a perspective view of the cooking device for use in the methodof the present invention;

FIG. 2 is a sectional view taken along the lines 2--2 in FIG. 1;

FIG. 3 is a sectional view of the upper portion of the apparatus for usein the present invention showing the electric motor, resistance heatingelement and the blower blade tank along the lines 3--3 in FIG. 1;

FIG. 4 is a view taken along the lines 4--4 in FIG. 2;

FIG. 5 is a fragmentary side view of the apparatus showing the topportion pivoted upwardly;

FIG. 6 is an exploded view of the heater unit as seen from beneath theunit;

FIG. 7 is a perspective view of an alternate cooking device;

FIG. 8 is a front view of the cooking device of FIG. 7;

FIG. 9 is a top view;

FIG. 10 is a rear view;

FIG. 11 is a bottom view;

FIG. 12 is a right side view;

FIG. 13 is let side view;

FIG. 14 is an exploded view of the power portion of the cooking device;

FIG. 15 is a cut view of the cooking device taken along he center linerunning from front to rear;

FIG. 16 is an enlarged exploded view of the heater coil of the cookingdevice;

FIG. 17 is an enlarged sectional view of the leg portion of the device;

FIG. 18 is an enlarged bottom view of a leg portion of the device.

FIG. 19 shows the hold down rack; and

FIG. 20 is a side view of the cooking device in FIG. 13 with theextension ring and the extension segment of the hinge support assembly.

DETAILED DESCRIPTION OF THE METHOD OF THE INVENTION

The method of the present invention includes placing the food product ina location in a self-contained countertop oven where the air current cansubstantially surround the cooking surfaces of the food piece. An aircurrent is the applied to the food piece at a velocity of at least 1000linear feet per minute desirably between 1200 and 2500 linear feet perminute. The velocity of the air stream may be as high as 4000 feet orhigher with certain food pieces so long as the food piece is notdisplaced. The temperature of the air is at least 125° F. desirablybetween 180 and 450° F.

The air current desirably is in the form of a cyclone shape whichrepeatedly recirculates within the cooking chamber in order to achieve avelocity of at least 1000 linear feet per minute. The cyclone helix mayhave both a straight vertical axis and a circular horizontal axis. Theair stream generally transverses the food piece in a path parallel tothe upper and lower surfaces of the food piece thus providing intimatecontact between the hot air stream and the food piece. This minimizesany air layer barrier adjacent to the surface of the food piece. Thedirection of the air current may be periodically reversed during thecooking cycle. The cyclone air flow may be used to rotate the tray thusproviding an interesting display of the food and improved visibility. Alow friction interface may be provided between the tray and the base ofthe cooker.

One cooing device 10 for carrying out the method of the presentinvention, as illustrated in FIGS. 1 through 6, includes a base member11, a top 12 and a powered heater unit 13. The heater unit 13 is inlocked engagement with top 12 as hereinafter described. The cookingdevice 10 further includes a lower frame bracket 14 and an upper framebracket 15. Brackets 14 and 15 may be hingedly interconnected such as byremovable pin 17. The brackets 14 and 15 may be integrally secured tothe base 11 and top 12 respectively, or alternatively, they may beremovably secured such as by snap mechanism 18.

The base 11 may be suitably formed of a polymeric material and includesa circumferential wall 21, an integral lower wall 22 and a plurality offeet 23. The feet 23 serve to elevate the lower wall 22 upwardly from asupport surface such as a countertop. The lower unit 11 may include athickened upper rim 24 defining a slot 26 into which the top 12 may belodged. The base 11 may include a handle 27. The circumferential wall 21has a plurality of small projections 28 which serve to support the rack29 on which the food pieces may be disposed. The rack 29 may be of aconventional wire construction as illustrated in FIGS. 1 and 2.

The top 12 of the cooking unit 10 likewise includes a circumferentialwall 31 and an upper wall 32. The wall 32 may be integral with wall 31.Top 12 may be produced by injection molding, or alternatively, vacuummolding. The upper wall 32 has an opening 32' defined therein forreceipt of the powered heating unit 13. The opening 32' may be definedby rim 33 including a thickened vertical wall 35 and aninwardly-extending wall 36.

The structure of the power heater unit 13 is illustrated in FIGS. 2, 3,and 6. The power unit 13 includes a motor portion 41, a heater 42 and ablower blade 43. The motor portion 41 includes an inner housing 44 whichmay be of sheet metal, an outer housing 46 which may be injection moldedplastic and a motor 47, including an armature 48 and a rotatably drivenshaft 49 which extends outwardly from each side of the armature. Therotational direction of the shaft may be reversed by reversing thefields of the motor. The motor 47 is mounted to the inner housing 44such as by a plurality of bosses 51 and screws 52. The screws 52 extendthrough suitable openings 53 in the upper wall 56 and anoutwardly-extending flange 57. The housing 44 is closed on the bottomside by plate 58. The plate 58 corresponds in dimension to the outeredge of the flange 57 such that the housing 44 rests on the rim 33 oftop 12. The housing 44 has an opening 59 for receipt of air for purposesof cooling the armature 48 as hereinafter described.

A plurality of snap mechanism 61 are attached by screws 62 at variouslocations around the periphery of the housing 44. The snap mechanism 61may be of spring sheet metal and serves to secure the motor portion 41to the top 12. Alternatively, a twist lock type of securement may beused to attach the power unit 13 to the top 12.

The housing 46 has a peripheral wall 69 and an integral upper wall 71 ahandle 72 may be moded as part of wall 69. The lower portion 73 of wall69 may be flared radially outwardly and includes a plurality of openings64 through which air may exit. The upper frame bracket 15 may beintegral with wall 69. The housing 46 may be secured to housing 44 suchas by flange 50 and screw 50a.

The heater 42 is an open coil, resistance wire type, and isthermostatically regulated to maintain cooking temperatures ranging from180 to 450° F. The heater 42 as shown in FIG. 6 may include an upperplate 76, a lower plate 77 and a resistance coil 78. The plates 76 and77 are of a material that does not conduct electrical current. The coil78 is sandwiched between plates 76 and 77 and thus electricallyinsulated from the remainder of the cooking device. The lower plate 77has a plurality of open zones 75 defined therein through which theheated air may move. The plates 76 and 77 may be secured together byrivets 81. Heater 42 (FIGS. 3 and 6) may be secured to plate 58 byscrews 82. The heater 42 is electrically connected to a source of powerthrough wires 83, switch 68 and cord 67.

The open heater coil 78 is used in order to achieve the lowest possiblesurface watt density. With adequate air flow, such an element is capableof transferring maximum heat to the air stream via conduction, whileoperating in the "black" heat range. In order for other types of heatingelements, such as tubular types, to give off the same wattage given thesame space and air flow, the heater would glow. Such a high surface wattdensity would result in overheating of the motor blower, the food beingcooked and plastic parts through an excessive radiation of heat. Inaddition, such an element would retain too much heat when the unit isshut off, causing additional overtemperature problems. It is to be notedthat the air current flow from blower blade 43 changes direction byabout 180° . Thus, any particulate material is thrown out of the aircurrent before the air passes over the heater coil 78. Any smoke,however, is recirculated over the coil and thus burned up or consumed.This is of course beneficial.

The heater assembly may also incorporate an over temperature devicecapable of shutting off power to the heater should the thermostat fail.

The power unit 13 includes an upper blade 63 which is mounted on shaft49 of motor 47. The blade 63 draws fresh air through the upper portionof bracket 15 as illustrated by the arrows in FIG. 2 and 3. The blade 63moves this cool fresh air upwardly around the motor 41 to cool themotor, up through openings 45 in housing 44 and downwardly and outwardlythrough the ports 64. The blower blade 43, which is mounted on theopposite end of shaft 49, moves the air currents within the heatedchamber. The blade 43 (FIG. 6) has an open central portion whichcorresponds with the open central portion 75 of the heater 42.

The blade 43 (FIG. 3) creates two air circulations. The first aircirculation is throughout the heated chamber. The second air circulationpasses a small portion of air over the heated coils in the heater 42 asillustrated in FIG. 3. In other words, the small air current exitsradially outwardly from the blade 43, reverses direction 180° to bedrawn in over the coil 78, then radially inwardly to the center of theheater 42, then downwardly into the center zone of the blade 43. Aprotective grid 66 may be provided over the blade 43. This directionreversal assures that no particulate material remains in the air streamthat contacts the coil 78.

Electrical current is fed into the device 10 by way of electric cord 67.The cord 67 may include a conventional plug for insertion into a wallsocket. The electrical current passes through switch mechanism 68mounted in the upper portion 15. The switch 68 includes a sensingmechanism to provide shutdown of the unit in the case of overheating inthe heating chamber and/or motor housing 41. The switch mechanism 68 mayalso include sensing mechanism to shut down the unit if the top portion12 is pivoted upwardly with the throw portion of the switch 68 in the"on" position.

OPERATION

Although the operation of this equipment is readily apparent from theaforedescription, it will be further described in order to provide amore complete understanding of the method of the present invention. Thecooking device may be accessed by pivoting the top portion 12 upwardlyas illustrated in FIG. 5. Food pieces such as potatoes, bakery goods,pizzas and the like may be placed on the rack 29. The top portion 12 isthen pivoted downwardly to the position illustrated in FIGS. 1 and 2.The switch 68 is then activated turning the heating element 42 and themotor 47 on. With the blade 43 rotating, air is moved within the chamberformed by the lower unit portion 11 and the upper portion 12. Air iscirculated over the resistance coil thereby providing heat to the airstream and in turn to the chamber. The temperature will typically be atleast 125° F. in the chamber. The temperature will preferably be in therange of 180-450° F. The air velocity in the heated chamber willtypically be over 1,000 linear feet per minute. The air velocity at thepoint where the air stream contacts the food pieces is between 1000 and4000 linear feet per minute. If desired, a central wall 69A may bemounted in the heated chamber to provide a change in the air flowpattern. In this case, one has two cyclone configurations. Unlike mostconventional cooking devices, the blower is placed in the top center ofthe cooking chamber. The blower wheel is mounted in such a way as toproject the air stream into the uppermost portion of the cookingchamber. The upper surface of the air stream being at the same level orslightly lower than the upper wall of the chamber. In this position, theair thrown off the wheel travels horizontally in parallel, with thelower surface of the upper wall 32 of the chamber unit. The air streamis directed downward by the radius joining the upper wall and thevertical round side wall. The air then travels downwardly in a spiraluntil it is again deflected at the base of the outside wall by theradius joining the side wall with the lower wall of the enclosure. Theair is then simultaneously pushed and drawn by the blower across bothabove and beneath the cooking rack. The rack 29 has handles 29a and maybe inverted to raise or lower the cooking surface. As the air approachesthe center of the enclosure, it is drawn up into the open underside ofthe blower blade 43, where it is then recirculated through the samepattern described above. A partial vacuum is drawn in the zone extendingdownwardly from the center of the blower blade.

The velocity of the air is not constant within the chamber, since theheated air converges as it moves to the center of the unit and is drawninto the blower. In the cooking device, the air cools as it contacts thefood, but simultaneously accelerates as it converges on the center ofthe chamber. This change in velocity compensates for the droppingtemperature by more effectively exchanging the heat remaining in theair. The result is very uniform cooking from the outer edge to thecenter of the cooking rack.

When cooking items that cover most of the cooking rack, such as a pizza,or that require a pan, such as cookies, air flow to the underside of therack is prevented from being drawn back into the blower wheel. Thetrapped air swirls rapidly, but cools off significantly, due toinadequate air exchange with the heated air mass above the rack. Tocompensate for the above, one or more "mixing vanes" 69A may be locateddiagonally under the cooking rack. This causes the air to form two ormore counter-rotating air masses that dramatically improve the airexchange under the rack (See FIGS. 1 and 2).

Because the present system is capable of developing very rapid air flowswith a minimum motor size and power input, it is desirable to equip thecooking device with an adjustable motor speed control. Some items, suchas cakes or pizzas with loose topping, should not be exposed to overlyhigh air speeds (e.g. should be about 1000 linear feet per minute). Whenpreparing such items, it is much preferred to reduce the air speed bylowering the motor speed. This results in a moderate extension ofcooking time, but still provides much more rapid cooking thanconventional ovens. Sensing mechanism may be provided to sense movementof the food materials and correspondingly reduce the air velocity to apoint immediately below that a which movement takes place. The open coilheater 78 is positioned directly above the blower blade 43. The bloweris fully open at the bottom, but also partially open on its top. As aresult, the blower draws most of its make-up air into is bottom side,but also draws air into its top. This causes a portion of the air thrownout from the circumference of the blower to reverse direction and bedrawn back through the heater perimeter, down through the open lowerplate of the heater assembly and into the semi-open top of the blowerwheel. This highly heated air is then mixed with the air being drawn infrom the bottom of the blower. This mixture is then thrown outhorizontally into the cooking chamber. This configuration provides thefollowing advantages. Most particles are unable to make the abrupt 180°change in direction made by the air drawn through the heater. The airtravelling through the heater assembly is virtually free ofcontamination, while most particles are thrown off to the sides andbottom of the cooking chamber, where they can easily be cleaned away. Asa result of the above, the heater does not accumulate food, oil orgrease, thereby eliminating the need to clean the heater. This alsoextends heater element life and prevents smoke or fire hazard.

Positioning the heater immediately above the blower saves substantialspace, and allows for the compact design of an easily-removed blowerassembly. When the assembly is removed, the entire cooking enclosure canthen be washed in a conventional household dishwasher. The compactnessallowed by the heater position leaves more visibility through the topwall of the transparent cooking enclosure, providing the user with amaximum view of the cooking operation. Due to the blower blades or wheelbeing located directly below the heater assembly, the blower wheelprovides additional mechanical protection to the heater while furtherreducing the risk of electrical shock to the user.

Cleaning of any food preparation appliance is always a primary concern.The cooking device is designed to be easily disassembled, allowing theentire two piece cooking enclosure to be emersed in water for soaking orwashing in a household dishwasher. The enclosure is molded of low-stickplastic capable of withstanding the maximum internal operationtemperature of at least 400° F. The blower assembly contains allelectrical components and easily mounts in the top half of the cookingenclosure, snapping in place by way of metal clips or by screwing intoplace, much like the lid on a jar. The blower assembly is dimensioned tofit easily inside the cooking enclosure for storage, thereby saving onscarce kitchen storage space and reducing shipping and packagingexpense.

The upper assembly is hingedly mounted on a detachable support whichconnects to the underside of the cooking enclosure. The cookingenclosure is opened by lifting up on the handle section 72 of the unitand pivoting the entire assembly rearward until it stops in a verticalposition. When the assembly is tilted rearward, an internal switch shutsoff all power to the motor and heater, thereby eliminating any danger ofinjury due to contact with the moving blower.

Due to the extensive use of plastics and the need to keep assemblytemperatures comfortable to the touch, internal cooking of the assemblymay be necessary. The motor must also be kept within safe operatingtemperature limits.

To achieve the above objectives, the blower unit 63 has been designed todraw cool, room temperature air in from directly above the hinge area.Drawing air from that point avoids taking in hot air rising off of thecooking enclosure. This cool air is pulled through the rectangularsegment connecting the motor enclosure to the hinge. This "duct" mayalso house electronic components that are heat sensitive or requirecooling, such as triacs. From here, the air is drawn over the motor, upthrough a secondary blower wheel 63 directly above the motor and thenexhausted downwardly around the outside walls of a "cup" 44 whichsurrounds the motor 48. This exhaust air is finally forced through a gap74 separating the cooking enclosure and the bottom edge of the blowerassembly. Here the air serves a valuable function of cooling the cookingenclosure plastic at its most vulnerable point, close to the heaterassembly.

Any deformation of the blower mount area due to over temperature troublemay render the cooking enclosure useless. Gussets may be molded into theblower mount area to act as stiffeners and cooling fins for the plastic.

When the blower is removed from the cooking enclosure, the user may theninstall optional attachments to convert the cooking device into asteamer, a corn popper or other application that would fit theconfiguration and features of the cooking enclosure.

ALTERNATE EMBODIMENT

A preferred cooking device 110 of the present invention is illustratedin FIGS. 7-18. Cooking device 110 includes a base enclosure member 111,an upper enclosure member 112 and an interconnecting member 113 forhingedly connecting member 111 with member 112. The device is thus aclamshell configuration with the upper enclosure being pivotableupwardly to provide access to the cooking chamber.

The lower enclosure member 111 (FIGS. 7 and 15) includes acircumferential wall 121 which is integral with lower wall 122. Feet 123support the lower wall 122 spaced upwardly from the surface on which thecooking device 110 is supported. The feet 123 may be of any desiredshape. Preferably the shape of feet 123 is such as to avoid accumulationof heat. One such preferred shape is illustrated in FIGS. 11 and 18,namely, "C"-shaped. The lower member 111 including walls 122 and 124 andfeet 123 may be suitably made of a polymeric material such as byinjection molding. The polymeric material may be opaque and decorativelycolored. The thicknesses of such walls and feet are sufficient toprovide structural support for the device 110. The upper portion 121a ofwall 121 may define a recess 126 for purposes of receving the upperenclosure member 112 as hereinafter described.

The upper enclosure member 112 (FIGS. 7 and 15) includes acircumferential wall 131 and an integral upper wall 132. The wall 132has an opening 132' that is defined by upstanding wall portion 132b. Theupper member 112 may be constructed of any suitable polymeric materialsuch as by injection molding. The polymeric materials used in members111 and 112 are suitable to withstand the operating temperatures of thecooker 110, e.g. temperatures of at least 400° F. the polymeric materialused in member 112 desirably is transparent thus enabling the user toobserved the food pieces during cooking. A typical polymeric material ispolyethersulphone.

In order to accommodate taller items such as loaves of bread or turkeys,the user may add one or more extension rings 208 to extend the height ofthe cooking enclosure. Extension segments 209 may also be added to thehinge support assembly 113 to match the extended height of the cookingenclosure.

The support member 113 (FIGS. 7, 12, 13 and 15) includes an uppersupport portion 114 and a lower support portion 115. The lower supportmember 115 has a horizontal leg 115a and a vertical leg 115b. The upperend of the vertical leg 115b has a concave portion 115c and a convexportion 115d.

The upper support member 114 is "L" shaped and has a horizontal leg 114aand a vertical leg 114b. The lower end of leg 114b has a convex portion114c and a concave portion 114d. A pivot shaft 115e runs between convexportion 115d and convex portion 114c.The convex portion 115d liescradled in concave portion 114d. The convex portion 114c lies cradles inconcave portion 115c. The upper support portion 114 pivots on shaft 115ewith respect to lower support portion 115.

The lower support portion 115 includes engagement mechanism 116 and 118which frictionally secures support member 113 to leg 123a of member 111.The engagement mechanism 116 and 118 may simply snap into engagementwith lugs 116a and 118a on the leg 123a.

The upper support portion 114 (FIGS. 14 and 15) includes a first housingportion 151, second housing portion 152 and rear housing portion 153.Housing portions 151-153 may be formed by injection molding. The housingportion 151 has a horizontal portion 151a and an integral verticalportion 151b.

The vertical portion 151a includes brackets 154a and 154b for securingthe motor 156 in place. The motor 156 may be held in place such as byscrews 157. An electrical cod 158 is electrically interconnected tomotor 156 through switch mechanism 159 and the safety lock-out mechanism111a, 112a and 113a. Suitable mechanism may be provided to convert ACcurrent to DC current if the motor 156 is a DC motor. A pulley 161 ismounted to the shaft 156a of motor 156. The hosing portion 152 ofsupport 114 serves to cover the upper side of portion 151 and may besecured in place by screws (not shown). Housing portion 152 has aremovable panel 152a which carries switch mechanism 159 and switchmechanism 192. The housing portion 153 serves to enclose support 114 tothe rear and may include a grille structure 153a through which air maypass to cool motor 156.

The hinged connecting member 113 (FIGS. 7, 14 and 15) has a heater -blower unit 160 mounted therein. Unit 160 has a base plate 166 which issecured to housing member 151 such as by screws 167. The base plate 166is constructed of an upper plate member 168 and a wire guard 169.

Heater assembly 171 (FIGS. 14-16) is mounted to the base plate 168. Theheater assembly 171 includes plate 172 on which is mounted a resistanceheating coil 173. The heating coil 173 may be of a nicklecadmeummaterial. Suitable connecting wires 174a are provided to connect theheating coil 173 with the switch mechanism 159. Heater assembly 171 hasa micra heater ring 174 and a heater cover 176. The mica heater ring 174serves to electrically insulate coil 173 from plate 172. The heaterassembly 171, mica heater ring 174 and heater cover 176 may be suitablysecured to the base plate 168 such as by screws 177.

The base plate 168 has a bearing 178 through which the shaft 179 ofsecondary blower assembly 181 may extend. The secondary blower 181serves to cool the upper metal portions of the heater assembly such asbase plate 168 and bearing 178. A primary blower blade 182 is secured tothe lower end of shaft 179. A spun fiber glass blanket 193 is held in acup shaped member 194 thereby shielding the bearing 178 from heat.

A flat drive belt 186 interconnects pulley 161 of motor 156 with theprimary blower blade 182 by way of the pulley 187 on secondary blowerassembly 181. The belt 186 is a flat belt such as is used as a timingbelt.

Suitable controls 159 and 192 controller respectively the electricalcurrent fed to heating coil 173 and speed of motor 156.

The cooker 110 may include a control circuit board 196 permitting thesetting of a single time-temperature-air velocity cycle or a complexseries of time-temperature-air velocity segments in a cycle. The cyclesmay be pre-established at the factory or may be created by thehomemaker. For example, the cycle may include a three step series forbaking a loaf of bread. The first step is at 170° F. for 5 minutes forrising of the dough, the second step is at 325° F. for baking the loafand the fourth step is at 450° F. for 5 minutes to crisp the crust ofthe loaf. The circuit board 196 may have a memory to store a pluralityof such complex series for later selective use. The series may includean activation time, e.g., turn on time. The cooking device 110 may havelights 204a-204d provide improved visibility of the food product duringcooking. Such lights may direct light from all sides of the oven 110.

The present cooking device 110 desirably includes safety mechanism 11Athat senses the presence of the lower or base member 111 and a mechanism112A which senses the presence of upper member 112. The mechanism 113Asenses the position of the upper member 112 to assure the device 110 isin a closed operating position before the blower 182 and coil 173 can beactivated.

The present invention cooking device 110 desirably includes an air ventscoop 198 to remove a portion of the air stream thereby reducing themoisture content and in turn increasing the speed of cooking. The airscoop 198 must extend downwardly from the lower surface of wall 132exposing an effective surface of between 0.1 and 0.3 square inches foreach cubic foot of cooking chamber. The preferred scoop has an effectivescooping surface of 0.17 square inch per cubic foot of cooking chamber.

The cooking device 110 may include a base liner 201 which may beconstructed of sheet metal shaped like a shallow pan. The base liner 201is spaced from wall 122 and catches any dropping juices of fats from thefood during cooking and thereby facilitates cooking. The base liner 201also serves as a partial heat barrier and reduces the heat escapingdownwardly through wall 122. The base liner 201 may have a non-stickcoating such as Silverstone™. A wire support or rack 202 may be mountedin the lower member 111. The wire support 202 serves to support footpieces 203 during cooking. The wire support 202 has handles 202a. Thewire support 202 may be inverted to raise or lower the cooking surface.In some instances a hold down rack 204 (FIGS. 15 and 19) may be providedto permit use of higher air velocities particularly with light weightfood pieces and yet avoid displacement of the food pieces. The hold downrack 204 may be of a wire construction similar to support 202. The holddown rack 204 may be supported on wire support 202 by legs 205, 206 and207. Each leg such as 205 may have three or more support notches such as205a, 205b and 205c.

OPERATION

While the operation of device 110 is apparent from the aforedescriptionwill be further described hereinafter in order to provide a morecomplete understanding of the invention. To operate the cooking device110, one connects the device 110 to household electrical current by wayof cord 158. The blower is then activated using control 159. Next thetemperature control 192 is adjusted to the appropriate operatingtemperatures. If one wishes to add some food pieces to the cookingdevice 110, one merely grasps the handle portion 114a pivoting the uppermember 112 upwardly on the shaft 13a. In so doing, the switchingmechanism deactivates the heater coil 173 and the motor 156. When theupper member 112 is again pivoted downwardly, the switching mechanismreactivates the motor 156 and the heater coil 173.

The blower is activated by providing electrical current to drive motor156 which then drives belt 186 carried on pulleys 161 and 187. Thepulley 187 drives secondary blade 181 and primary blower blade 182.Blade 181 draws in fresh air which cools motor 156 and other portions ofthe present cooking device such as base plate 168. The blower blade 182creates a primary air flow in a downwardly directed cyclone pattern tocook food pieces and a secondary flow which passes over the electricalcoil 173. The heated air is commingled then with the primary air flow.

While various specific details are described with respect to thisembodiment of the invention, it is to be recognized that variousmodifications may be made without departing from the broader scope ofthe present invention.

What is claimed is:
 1. An oven comprisingan upper enclosure member; anextension ring portion comprising at least one extension ring; a lowerenclosure member, wherein said upper enclosure member, said extensionring portion and said lower enclosure member cooperatively define acooking chamber; means for moving air inside said cooking chamber at aspeed of at least 1000 linear feet per minute; means for heating air insaid cooking chamber to a temperature over 180° F.; and a hinge supportassembly comprising an upper support, an extension portion, and a lowersupport, wherein said extension portion comprises at least one extensionsegment, wherein said upper support is connected to said upper enclosuremember and to said extension portion, and wherein said lower support isconnected to said extension portion and to said lower enclosure member.2. The oven of claim 1 wherein said extension rings are selectivelyremovable.
 3. The oven of claim 1 wherein said extension ring portionconsists of one extension ring which is selectively removable.
 4. Theoven of claim 1 wherein said extension segments are selectivelyremovable.
 5. The oven of claim 1 wherein said extension portionconsists of one extension segment which is selectively removable.
 6. Theoven of claim 1 wherein aid hinge support assembly comprises: p1 a hingedisposed between said upper support and said lower support.
 7. The ovenof claim 6 wherein said hinge comprises a removable pin.
 8. The oven ofclaim 1, wherein said lower support comprises a snap mechanism whichengages said lower enclosure member.
 9. The oven of claim 1 wherein saidextension ring portion has a height, wherein said extension portion hasa height, and wherein said height of said extension ring portion matchessaid height of said extension portion.
 10. An oven comprising:a lowerenclosure member; an upper enclosure member, wherein aid upper enclosuremember is disposed above said lower enclosure member, wherein aid lowerenclosure member and said upper enclosure member cooperatively define atleast a portion of a cooking chamber; means for heating air inside saidcooking chamber; an interconnecting member comprising an upper support,and a lower support, wherein said upper enclosure member is connected tosaid upper support, wherein said upper support is connected to said tosaid lower support, and wherein said lower support is connected to saidlower enclosure member, and interconnecting extension means forextending said interconnecting member.
 11. The oven of claim 10 furthercomprising:cooking chamber expansion means for expanding said cookingchamber.
 12. The oven of claim 11 wherein the cooking chamber expansionmeans comprises:an extension ring portion, wherein said extension ringportion is disposed between said upper enclosure member and said lowerenclosure member, and wherein said extension ring portion comprises atleast one extension ring.
 13. The oven of claim 12 wherein saidextension ring portion consists of one extension ring.
 14. The oven ofclaim 11 wherein said cooking chamber expansion means has a height,wherein said interconnecting extension means has a height, and whereinsaid height of said cooking chamber expansion means is roughlyequivalent to said height of said interconnecting extension means. 15.The oven of claim 10 wherein said interconnecting extension meanscomprises at least one extension segment interposed between said uppersupport and said lower support.
 16. The oven of claim 15 wherein saidextension segments are selectively removable.
 17. The oven as claimed inclaim 15 wherein said interconnecting extension means consists of oneextension segment which is selectively removable.
 18. The oven of claim15 wherein said interconnecting member is hinged.
 19. An ovencomprising:an upper enclosure member and a lower enclosure member, saidupper and lower enclosure members fitting together to form a cookingchamber having a height, said cooking chamber being generally circularin horizontal cross section; means for moving air inside said cookingchamber; means for heating air inside said cooking chamber; and cookingchamber extension means for extending the height of said cookingchamber, said cooking chamber extension means comprising at least oneextension ring which is removably located between said upper and lowerenclosure members to extend the height of said cooking chamber.
 20. Theoven of claim 19, further comprising an interconnecting member, saidinterconnecting member comprising an upper support connected to saidupper enclosure member, a lower support connected to said lowerenclosure member, said upper and lower support being fitted together todefine a height of said interconnecting member.
 21. The oven of claim20, wherein said interconnecting member further comprisinginterconnecting extension means for extending the height of saidinterconnecting member, said interconnecting extension means comprisingat least one extension segment which is removably located between saidupper and lower supports to extend the height of said interconnectingmember.
 22. The oven of claim 21, wherein said upper enclosure memberhas an opening located therein, said oven further comprising a housingto which said air moving means and said air heating means are attached,said housing being mounted over said opening.
 23. The oven as claimed inclaim 22, wherein said upper support of said interconnecting member isattached to said housing.
 24. The oven of claim 19, wherein aid airmoving means moves the air in said cooking chamber at a speed of atleast 1000 linear feet per minute.
 25. The oven of claim 19, whereinsaid upper enclosure member has an opening located therein, said ovenfurther comprising a housing to which said air moving means and said airheating means are attached, said housing being mounted over saidopening.
 26. The oven as claimed in claim 25, wherein said air movingmeans comprises a lower blade mounted below the heating means.